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  • Articles: DFG German National Licenses  (2)
  • 1985-1989  (1)
  • 1980-1984  (1)
  • Chromium
  • Cotransport
  • Electron microscopy
  • Polymer and Materials Science
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  • Articles: DFG German National Licenses  (2)
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  • 1
    ISSN: 1432-072X
    Keywords: Bradyrhizobium ; Electron microscopy ; Mutants ; Nitrogen fixation ; Nodulation ; Soybean ; Symbiosis ; Transposon Tn5
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genome of the slow-growing Bradyrhizobium japonicum (strain 110) was mutagenized with transposon Tn5. A total of 1623 kanamycin/streptomycin resistant derivatives were screened in soybean infection tests for nodulation (Nod) and symbiotic nitrogen fixation (Fix). In this report we describe 14 strains possessing a stable, reproducible Nod+Fix- phenotype. These strains were also grown under microaerobic culture conditions to test them for free-living nitrogen fixation activity (Nif). In addition to strains having reduced Fix and Nif activities, there were also strains that had reduced symbiotic Fix activity but were Nif+ ex planta. Analysis of the genomic structure revealed that the majority of the strains had a single Tn5 insertion without any further apparent physical alteration. A few strains had additional insertions (by Tn5 or IS50), or a deletion, or had cointegrated part of the vector used for Tn5 mutagenesis. One of the insertions was found in a known nif gene (nifD) whereas all other mutations seem to affect different, hitherto unknown genes or operons. Several mutant strains had an altered nodulation phenotype, inducing numerous, small, widely distributed nodules. Light and electron microscopy revealed that most of these mutants were defective in different stages of bacteroid development and/or bacteroid persistence. The protein patterns of the mutants were inspected by two-dimensional gel electrophoresis after labelling microaerobic cultures with l-(35S)methionine. Of particular interest were mutants lacking a group of proteins the synthesis of which was known to be under oxygen control. Such strains can be regarded as potential regulatory mutants.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 11 (1980), S. 244-258 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Behaviour of stainless cast alloys under combined mechanical and corrosive attackIn media with 3000 mg B/1 (as boric acid, H3BO3) and varying chloride contents down to 1 mg Cl-/1 13%-Cr-steels show pitting. Under constant load cracks appear simultaneously. As can be expected, 17%-Cr-steels are more resistant and duplex ferritic austenitic steels exhibit no corrosion cracking in 3% NaCl-solution even after 10 000 hrs. Generally, corrosion resistance improves with increasing contents of ferrite forming elements. Corrosion cracks are interpreted in termes of anodic stress corrosion cracking. Notch impact bending tests with hydrogen charged specimens show that deformability is reduced.
    Notes: 13%-Cr-Stähle zeigen in Lösungen mit 3000 mg B/1 (als Borsäure, H3BO3) und unterschiedlichen Chloridgehalten Lochkorrosion bis herab zu Konzentrationen von 1 mg Cl-/1. Bei mechanischer Zugbeanspruchung treten gleichzeitig Risse auf. 17%-Cr-Stähle sind erwartungsgemäß beständiger und ferritisch-austenitische Stähle zeigen in 3% NaCl-Lösung auch im 10 000 h-Versuch keine Korrosionsrisse. Generell steigt die Beständigkeit mit zunehmendem Anteil an ferritbildenden Elementen. Die Korrosionsrisse werden als anodische Spannungsrißkorrosion interpretiert. Kerbschlagbiegeversuche mit wasserstoffbeladenen Proben ergeben eine Abnahme des Verformungsvermögens.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
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